1. Field of the Invention
This invention relates to apparatus or systems for use in roof construction work, particularly but not exclusively for large industrial buildings during erection or maintenance of roof structures.
2. State of the Art
The construction and more particularly the maintenance, repair or replacement of roof structures in large industrial buildings such as factory roofs presents numerous problems, particularly with ensuring the safety of workers. For example, factory roof structures sometimes need major work including replacement as a result of deterioration after years of use. Some factories produce or use corrosive substances which are present in the atmosphere in the factory and over periods of time can cause severe corrosion of roof structures including the roofing materials and the support structure for the roofing materials including particularly roof purlins. Such corrosion and deterioration of roofing materials and the roof support structure can make it particularly dangerous to attempt to repair or replace the roof structure by walking on the roof. To solve this problem it has been usual in the past to erect scaffolding within the factory to enable the maintenance or replacement of the roof structure by workmen supported by the temporary scaffolding erected for the purpose. However, the erection and disassembly of such scaffolding can be time consuming and expensive and can substantially interfere with normal operations in the factory.
U.S. Pat. No. 4,676,341 (Shaffstall) discloses a pitched roof mounted construction scaffold for providing a horizontal platform enabling work to be carried out on a vertical or inclined surface adjacent to the pitched roof on which the scaffold is erected. The scaffold is not movable.
U.K. patent specification 2,192,660 (Robathan) discloses a kit of parts for assembly into a pitched roof mounted construction scaffold. Robathan also provides a horizontal platform enabling work to be carried out beyond the boundary of the platform. The Robathan scaffold is assembled in situ and is not movable.
Each of Shaffstall and Robathan provides a scaffold which rests at its lower end on the roof itself and the roof drops further away from the horizontal platform in the outwards direction, so neither enables work to be carried out on the pitched roof itself